This invention relates to supramolecular compounds comprising a single quadruple hydrogen bonding unit that are capable of forming at least four H-bridges with each other in a row leading to physical interactions between different supramolecular compounds. These physical interactions originate from multiple hydrogen bonding interactions (supramolecular interactions) between self-complementary units comprising at least four hydrogen bonds in a row. Units capable of forming at least four hydrogen bonds in a row, i.e. quadruple hydrogen bonding units, are in this patent application abbreviated as 4H-units. Sijbesma et al. (U.S. Pat. No. 6,320,018; Science 1997, 278, 1601; incorporated by reference herein) discloses 4H-units that are based on 2-ureido-4-pyrimidones. These 2-ureido-4-pyrimidones in their turn are derived from isocytosines.
Polymers modified with two or three 4H-units have been prepared (Folmer, B. J. B. et al., Adv. Mater. 2000, Vol. 12, 874; Hirschberg et al., Macromolecules 1999, Vol. 32, 2696; Lange, R. F. M. et al., J. Polym. Sci. Part A, 1999, 37, 3657-3670; all incorporated by reference herein). However, these polymers need at least two 4H-units per chain in order to get a significant higher molecular weight via self-assembly, that is critically needed to obtain polymeric compound properties. Moreover, it has been reported that the presence of monofunctional 4H-units in these compounds leads to a strong decrease in their compound properties (Folmer, B. J. B., PhD thesis TU Eindhoven, 2000, Chapter 4; incorporated by reference).
Polymers with a relative large number of 4H-units grafted on the main chain have been obtained by copolymerizing an olefin bearing a 4H-unit with a common olefin (Coates, G. W. et al., Angew. Chem. Int. Ed., 2001, Vol. 40, 2153; incorporated by reference), or by copolymerizing a diisocyanate functional 4H-unit with polyether or polyester diols (EP 1.687.378; incorporated by reference). In this way, reversible cross-links are introduced via hydrogen bonding resulting in polymeric compound properties for these self-assembling polymers. However, in all these cases relative large molecular weight polymers are obtained resulting in relative large melt viscosities. Hence, efficient melt-processing of such compounds is limited.
Dyes containing only one 4H-unit are disclosed in EP 1.310.533, incorporated by reference, the resulting dyes are used in ink-jet compositions because of their increased light fastness. Examples are disclosed that are constituted from a 4H-unit coupled to aromatic dyes via linker molecules such as diisocyanates. However, because these dyes consist of large aromatic systems, their melting point is significant higher than 45° C. and therefore the resulting molecules are crystalline powders in nature and they do not show polymeric compound properties like good film forming and ductile behaviour.
Phase-change inks are disclosed in US 2003/0105185, incorporated by reference. These inks contain an ink-vehicle that is a compound containing one to four 4H-units per molecule. Glycerine and sucrose-based polyols functionalized with two to four 4H-units are disclosed in Examples V-VIII of this patent application, resulting in polymeric molecules of high molecular weights and therefore high melt viscosities. Additionally, in Example XVII, molecules are disclosed consisting of a 4H-unit with linear C1 to C18 alkyl-chains directly coupled to it, resulting in crystalline organic compounds with sharp melting points. Consequently, the monofunctional compounds in this Example XVII behave like normal organic compounds and do not show polymeric compound properties like good film forming and ductile behaviour.
Liquid-crystalline molecules containing one 4H-unit have been prepared (Hirschberg et al., Chem. Eur. J. 2003, 4222; incorporated by reference). In order to induce liquid crystallinity in these compounds it was necessary to have a large mesogenic system (3,4,5 tri-alkoxy phenyl) on the 6-position of the isocytosine ring that constitutes the 4H-unit. Therefore, multiple synthetic steps are necessary to obtain a precursor of the 4H-unit that contains this large aromatic system including the synthesis of a custom-made β-keto-ester. Moreover, the compound properties and possible applications of these compounds are not disclosed.
Water dispersable compounds containing one 4H-unit have been prepared (Menger et al., J. Am. Chem. Soc. 2006, 1414; incorporated by reference). The compound contains a cholesterol moiety linked to a 4H-unit via an oligoethylene glycol linker. This hydrophilic linker is needed to suspend the molecule into water as demonstrated in this paper. Clearly, this hydrophilicity excludes the use of this compound in applications were atmospheric water is present as this will have a detrimental effect on the compounds properties.
Example 9 of WO 2004/016598, incorporated by reference, discloses a compound having one 4H unit, said compound containing a polar PEG-MA group which is linked to the 4H unit by a hexamethylene group.
WO 2007/072000, incorporated by reference, discloses compounds according to Formula (II) wherein polymeric groups having a molecular weight of 200-500.000 are linked to at least two 4H units.
WO 2008/063057, incorporated by reference, discloses supramolecular polymers comprising 1-50 4H units by reacting 4H units bearing at least one functional group with a prepolymer having preferably at least two complementary functional groups.
There is a need in the art for low molecular weight supramolecular compounds having a low melt viscosity and which are easy to process and still show supramolecular behaviour. Such supramolecular compounds would be very useful for coating, adhesive and ink compositions.